通过测量电场获取电力设备实际遭受的过电压对于电力系统故障分析、电力设备绝缘耐受试验标准制定具有重要的指导意义。为此,提出了一种基于集成光学电场传感器的过电压测量技术。首先,介绍了该测量技术的基本原理;其次,研制了集成光学...通过测量电场获取电力设备实际遭受的过电压对于电力系统故障分析、电力设备绝缘耐受试验标准制定具有重要的指导意义。为此,提出了一种基于集成光学电场传感器的过电压测量技术。首先,介绍了该测量技术的基本原理;其次,研制了集成光学电场传感器,并对过电压测量系统的响应速度、频率响应等性能指标进行了测试;最后,采用所提出的测量技术对220 k V母线投入电容式电压互感器(CVT)、投入避雷器期间产生的过电压分别进行了测量。结果表明:过电压测量系统的响应速度达μs级,频率响应在5 Hz^100 MHz内比较平坦;在投入CVT和避雷器的暂态过程中,过电压上升时间约为几μs,过电压倍数可达1.73倍。测量结果反映的物理过程与理论分析一致。展开更多
In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguis...In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguishing features are revealed.Firstly,the inertial response characteristics of VSG controlled WFs(VSG-WFs)are impaired by the dynamic coupling.Secondly,when the influence of WTRSR is dominant,the inertial response characteristics of VSG-WFs are even worse than the condition under which WFs do not participate in the response of grid frequency.Thirdly,this phenomenon cannot be eliminated by only enlarging the inertia parameter of VSG-WFs,because the influence of WTRSR would also increase with the enhancement of inertial response.A decoupling scheme to eliminate the negative influence is then proposed in this paper.By starting the WTRSR process after inertial response period,the dynamic coupling is eliminated and the inertial response characteristics of WFs are improved.Finally,the effectiveness of the analysis and the proposed scheme are verified by simulation results.展开更多
To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invari...To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.展开更多
Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum ...Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.展开更多
文摘通过测量电场获取电力设备实际遭受的过电压对于电力系统故障分析、电力设备绝缘耐受试验标准制定具有重要的指导意义。为此,提出了一种基于集成光学电场传感器的过电压测量技术。首先,介绍了该测量技术的基本原理;其次,研制了集成光学电场传感器,并对过电压测量系统的响应速度、频率响应等性能指标进行了测试;最后,采用所提出的测量技术对220 k V母线投入电容式电压互感器(CVT)、投入避雷器期间产生的过电压分别进行了测量。结果表明:过电压测量系统的响应速度达μs级,频率响应在5 Hz^100 MHz内比较平坦;在投入CVT和避雷器的暂态过程中,过电压上升时间约为几μs,过电压倍数可达1.73倍。测量结果反映的物理过程与理论分析一致。
基金supported by Science and Technology Project of State Grid Corporation of China(No.5102-201956300A-0-0-00)。
文摘In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguishing features are revealed.Firstly,the inertial response characteristics of VSG controlled WFs(VSG-WFs)are impaired by the dynamic coupling.Secondly,when the influence of WTRSR is dominant,the inertial response characteristics of VSG-WFs are even worse than the condition under which WFs do not participate in the response of grid frequency.Thirdly,this phenomenon cannot be eliminated by only enlarging the inertia parameter of VSG-WFs,because the influence of WTRSR would also increase with the enhancement of inertial response.A decoupling scheme to eliminate the negative influence is then proposed in this paper.By starting the WTRSR process after inertial response period,the dynamic coupling is eliminated and the inertial response characteristics of WFs are improved.Finally,the effectiveness of the analysis and the proposed scheme are verified by simulation results.
基金Project(61074099)supported by the National Natural Science Foundation of ChinaProject(LJRC013)supported by Cultivation Program for Leading Talent of Innovation Team in Colleges and Universities of Hebei Province,ChinaProject(B705)supported by Doctor Foundation of Yanshan University,China
文摘To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.
基金Funded by the National Natural Science Foundation of China(No.60974049)the Science and Technology Support Industrial Project of Jiangsu Province(No.BZ2008031,No.BE2008074,and No.BE2009090)+1 种基金the Nantong International Cooperative Project(No.W2009003)the Natural Science Foundation of Nantong University(No.08Z022 and No.08Z025).
文摘Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.
